The present invention relates to a method and apparatus for heating a fluid stream and more particularly to a unique and novel method and apparatus for heating a gas or a liquid with compressed combustible fuel gas and compressed gas for supporting the efficient combustion of such fuel gas.
It long has been known to conduct and inject into a combustion burner a fluid combustible fuel through the chamber of a central conduit and to conduct and inject therewith a combustion supporting fluid into the burner through an annular passage defined by another conduit spaced from and surrounding the central conduit. In this regard, attention is directed to long expired U. S. Pat. No. 405,391, issued to P. L. Bear on Jun. 18, 1889, which patent broadly teaches such an arrangement for an oil burner and to long expired U.S. Pat. No. 622,146, issued to G. Heysel on Mar. 28, 1899, which patent broadly teaches another such arrangement for a hydrocarbon burner. Further attention is directed to unexpired U.S. Pat. No. 3,902,840, issued to Paul Baguet on Sept. 2, 1975, which also teaches two coaxial injectors for a fuel gas and combustion supporting gas, this patent further teaching a combustion chamber having a narrowing outlet. In this regard, attention is further directed to expired U.S. Pat. No. 2,652,890, issued to C. W. Morck, Jr., et al on Sept. 22, 1953 and to U.S. Pat. No. 3,424,541, issued to R. Wang, et al on Jan. 28, 1969, both of which teach such a refractory lined combustion chamber, attention being further directed to the coaxial injection apparatus disclosed by the Wang patent. Finally, attention is directed to the coiled heat exchange arrangement of unexpired U.S. Pat. No. 4,161,391, issued to Herbert W. Parker on Jul. 17, 1979 and to the reduced heat exchange tubes taught by expired U.S. Pat. No. 2,182,218, issued to J. C. Woodson on Dec. 5, 1939 and by unexpired U.S. Pat. No. 4,218,211, issued to Stanley Z. Caplan on Aug. 19, 1980. A number of other patents noted as of possible interest relating to the mixing of gases for burning are as follows: U.S. Pat. Nos. 993,687, issued to B. F. Jackson on May 30, 1911; 1,921,059, issued to J. M. Weil, et al on Aug. 8, 1933; 2,340,120, issued to H. L. Grupp on Jan. 25, 1944; 2,526,748, issued to N. E. Hill on Oct. 24, 1950; 2,838,105, issued to D. Eastman, et al on Jun. 10, 1958; and 3,074,469, issued to R. P. Babbitt, et al on Jan. 22, 1963.
Although a number of these several aforementioned patents might each broadly and separately have suggested coaxial injection apparatus, refractory lined combustion chamber apparatus narrowing at the outlet end thereof, coiled heat exchange tubes and heat exchange change tubes narrowing at the outlet thereof, none of these aforementioned patents, either alone or in combination with each other, recognizes or teaches a solution of the problems recognized and resolved by the inventive method and apparatus as is disclosed in this application.
The present invention recognizing past limitations in manufacture, assembly, installation and performance of prior furnace assemblies and in methods for heating gases and liquids, teaches a new and unexpected method and apparatus which considerably surmounts past limitations in the heat exchange art, providing a readily and economically manufactured, assembled, installed, maintained and repaired or replaced heat exchange system and parts thereof, the inventive system being capable of producing high and efficient performance over a broad range of turn-up and turn-down operating conditions. More specifically, the present invention provides a highly efficient, very compact heat exchange system which allows for operation at comparatively higher velocities and pressures to entrain and purge the system of corrosive condensation and other combustion outfalls, the arrangement of the present invention providing extremely high heat transfer efficiencies in a comparatively and considerably smaller equipment space with minimum standby losses. Further, the present invention provides a novel furnace assembly and method of operation which obtains a high ignition rate of reaction with a comparatively inexpensive venting system that reduces construction and insulation costs, avoids roll out of flame or gas, avoids undesirable chimney effects and minimizes standby losses. In addition, the method and apparatus of the present invention is readily adaptable to a large range of construction and processing environments with a capability of operating efficiently and quietly in a minimum of space and with a minimum of safety hazards due to a sealed pressure vessel combustion chamber arrangement.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.